Device for producing white smoke by imploding red phosphorus

ABSTRACT

A device for producing white smoke having an inner core of red phosphorus surrounded by a flexible sheet of explosive material and having means for detonating said explosive material whereby red phosphorus is imploded to produce white smoke.

United States Patent Inventors Appl. No. Filed Patented Assignee DEVICE FOR PRODUCING WHITE SMOKE BY IMPLODING RED PHOSPl-IORUS 3 Claims, 2 Drawing Figs.

U.S. Cl 102/90, 102/65, 102/66 F42b 13/44 102/1, 6, 32, 39, 66, 98, 87, 65

Primary Examiner- Robert F. Stahl Attorneys-R. S. Sciascia, 1-1. H. Losche and Paul S. Collignon ABSTRACT: A device for producing white smoke having an inner core of red phosphorus surrounded by a flexible sheet of explosive material and having means for detonating said explosive material whereby red phosphorus is imploded to produce white smoke.

1 M t/r/IA 1e PATENTED DEC 7 I97! INVENTORS BERNARD E. 00004 By noscoz 0. DW/GGI/VS 477 was m fi Zww n 5 a r Wm H S DEVICE FOR PRODUCING WHITE SMOKE BY IMPLODING RED PI-IOSPI-IORUS STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION The present invention relates to a device for producing white smoke by imploding red phosphorus.

Chemicals in the category of screening smokes are those which, when dispersed in air, produce a cloud of finely divided particles of solid, liquid, or both. These are used to shield tactical operations or disrupt the movements of the enemy. Outstanding examples of such materials are: fuel oil used in artificial fog generators, white phosphorus, sulfur trioxide, titanium tetrachloride, and so-called zinc chloride smokes. Each of the above-listed smoke-generating compositions is characterized by certain advantages and disadvantages in military operations, depending upon the importance of such factors as mobility of the smoke-producing apparatus, toxicity, logistical considerations, and the total obscuring power of the composition employed.

Traditionally, the Military has used white phosphorus as the load in munitions designed to provide a white smoke mark. The method employed is to explode the white phosphorus by means of a high-explosive center core. The white-pillaring cloud produced is the product of combustion of the white phosphorus with the oxygen from the surrounding atmosphere. Since white phosphorus is spontaneously reactive with air (pyrophoric) upon dispersal into the atmosphere, the conversion of the white phosphorus to smoke approaches 100 percent.

There are, however, several notable disadvantages to the use of white phosphorus in military hardware, such as increased cost to load due to the pyrophoric nature of white phosphorus, low melting point (44.3" C.), which may cause center of gravity shifts if the load melts, and danger of leakage from containers and shells. Also, presently there is only one production facility in the United States which can load white phosphorus.

It has been observed in the past that red phosphorus will produce a white smoke cloud comparable to that produced by the white form if combustion is complete. In addition, as the red phosphorus is a solid up to 597 C., and is not pyrophoric. it does not have many of the disadvantages of the white form. Additionally, about every commercial pyrotechnic company has the facilities and capability to load red phosphorus, thus insuring competitive bidding and competition.

The main reason ihat red phosphorus was never universally substituted for white phosphorus in smoke marking munitions is that it was extremely difficult to achieve complete combustion of the red form with existing technology. It was conventionally necessary to explode the phosphorus into the atmosphere to generate the smoke cloud. Such action would result in an excellent white cloud when white phosphorus was used. On the other hand. however, when the red form was used, not all of the phosphorus was ignited during the explosion. This resulted in incomplete combustion and consequently, a smoke cloud of reduced size and density was formed.

SUMMARY OF THE INVENTION The present invention relates to a device for producing white smoke by using red phosphorus. Red phosphorus pellets are wrapped with a flexible plastic explosive and loaded into a thin-walled container or shell. Upon detonation of the flexible plastic explosive, nearly complete combustion is achieved by implosion of red phosphorus thereby producing a smoke cloud similar to that formed from explosion of an equal amount of white phosphorus.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal sectional view of a preferred embodiment of the present invention; and

FIG. 2 is a sectional view taken on line 2-2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, there is shown a smoke bomb having a cylindrical body section 11 to which a nose section 12 is threadedly attached. A suitable fuze I3 is provided in nose section 12 and, by way of example, fuze 13 might be either a point-detonating nose fuze or a proximity fuze, both of which are well known to those skilled in the art. An inner core of red phosphorus 14 is provided in cylindrical body section 1 l, and this red phosphorus 14 might either be in granular form or be mixed with a suitable binder and formed in pellets. A sheathing of flexible high explosive I5 is positioned between body section 11 and the red phosphorus l4 and explosive I5 completely surrounds red phosphorus 14. By way of example, the sheathing of flexible high explosive 15 might be Detasheet, a flexible plastic-bonded form of high explosive marketed by E. l. DuPont deNemours and Co., Wilmington, Delaware. A detonating booster 16, such as tetryl pellet, is provided in the forward end of body section 1 1 to detonate high explosive l5.

OPERATION Cylindrical body section 11 is provided with external threads 17 so that body section 11 can be attached to a rocket or other delivering device. Upon actuation of fuze l3, booster I6 is detonated which, in turn, detonates high explosive 15 thereby imploding red phosphorus 14.

In a test conducted at Naval Ammunition Depot, Crane, Indiana red phosphorus pellets were wrapped with Detasheet and placed in a 2.75 inch rocket head. The rocket head cavity was about 18 inches long and had an inside diameter of 2.5 inches. The rocket head was made of aluminum and had a 0.l25-inch thick wall. Loaded rocket heads were statically fired while positioned horizontally on the ground and the implosion of the red phosphorus resulted in the formation of a huge smoke cloud. Inspection of the test area after firing did not reveal any significant amount of unconsumed red phosphorus and it was concluded that nearly complete combustion was achieved by imploding red phosphorus.

The smoke cloud resulting from implosion of red phosphorus is similar to that formed from explosion of an equal amount of white phosphorus. In the text, Phosphorus And Its Compounds, Vol. I, by John R. Van Wazer, (Interscience Publishers, Inc. I958), at page 10 I, it is explained that molten red phosphorus yields white phosphorus upon rapid cooling. It is believed that the heat and pressure generated when red phosphorus is imploded causes some of the red phosphorus to melt and this liquid, upon rapid cooling, forms white phosphorus which subsequently burns upon contact with the atmosphere. This phenomenon, in combination with the pillared-dispersal of the red phosphorus, is believed to account for the superior manner of making a smoke cloud when red phosphorus is imploded.

We claim:

1. A white smoke producing device comprising,

a cylindrical housing,

an inner core consisting entirely of red phosphorus within said housing,

a layer of flexible plastic-bonded high explosive positioned between said inner core of red phosphorus and the inside wall surface of said cylindrical housing and surrounding said inner core of red phosphorus, and

means for detonating said layer of flexible plastic-bonded high explosive whereby said inner core of red phosphorus is imploded to produce white smoke.

2. A white smoke producing device as set forth in claim 1 wherein said red phosphorus is in granular form.

3. A white smoke producing device as set forth in claim 1 wherein said red phosphorus is in pellet form.

I i t i 

1. A white smoke producing device comprising, a cylindrical housing, an inner core consisting entirely of red phosphorus within said housing, a layer of flexible plastic-bonded high explosive positioned between said inner core of red phosphorus and the inside wall surface of said cylindrical housing and surrounding said inner core of red phosphorus, and means for detonating said layer of flexible plastic-bonded high explosive whereby said inner core of red phosphorus is imploded to produce white smoke.
 2. A white smoke producing device as set forth in claim 1 wherein said red phosphorus is in granular form.
 3. A white smoke producing device as set forth in claim 1 wherein said red phosphorus is in pellet form. 